Ovulation is a precisely timed event in which a mature oocyte is released from an ovarian follicle. The ovulatory process is associated with the transcriptional regulation of numerous genes, including the upregulation of CCAAT/enhancer binding protein [unreadable] (Cebpb), a nuclear receptor transcription factor, within the periovulatory granulosa cell. The essential role of Cebpb in the ovulatory process has been demonstrated by gene targeting which completely blocked follicular rupture in nullizygous females. The long-term objective of the experiments outlined in this proposal are to identify the Cebpb regulated gene(s) in periovulatory granulosa cells that are essential for completion of the ovulatory process. Recently, our laboratory utilized a new methodology referred to as chromatin immunoprecipitation (CHIP) that allows us to identify regional changes in chromatin structure and correlate those changes with increased gene activity (transcription). Additionally, this methodology allows the in vivo trapping of transcription factors to their target regulatory elements in multiple genes simultaneously. We will adapt this new methodology to identify unknown genes that are regulated directly by Cebpb within ovarian granulosa cells. The rationale that underlies the proposed research is that as genes are identified mechanisms will be elucidated to gain a better understanding of the process of ovulation. The PI has expertise in reproductive biology experiments and molecular techniques and has used the methodology to identify other genes involved in the process of ovulation. The collaborator has an extensive background examining Cebpb transcriptional regulation. She also has generated mice deficient in Cebpb. Therefore, the PI and collaborator combine unique talents that provide the necessary resources and skills to complete the research goals in the current proposal. These studies will for the first time determine the mechanism and cell signaling pathways by which the Cebpb transcription factor promotes ovulation. [unreadable] [unreadable]